DIY Rock Wall / River Tank (long with pics)

I'm making a rock wall with a river of sorts that runs down the wall from one side to the other and back, in a 30gl. I plan to put a couple newts in it for my son. I'll try to walk you through the process. I hope it turns out & is safe for the inhabitants and holds up with time. I've used the info I've found on this site from several peoples adventures. I have mixed matched and used what I thought would work out the best, cheapest, and easiest.
This is what I came up with.....

Okay, let's start of with " What a project!" This was a lot of work. It was a good core workout. LOL My back & core were pretty sore from leaning over this thing so much. Take on a project like this & you'll get balls of cement! I sure did!



I'll start with the supplies needed. Well, the ones I've used so far. I'll have to include the silicone, intake strainer, and filter stuff later.
To this point, I've had to use:
One 2" sheet of Styrofoam 4x8 $12. Home Depot. I only used about 1/4 of the sheet. If that. (it's behind the saw)


Quikrete Hydraulic cement 20lb. $13 (building supply place) , Cement color (charcoal color) $6 Home Depot, Mixing bucket $1, brush $2


Great stuff $5. Home Depot

Okay, time for the tool listing. There are sooooo many ways you could do this. Use your imagination & use what you have. Don't run out and buy any fancy tools for this job. You can make due, trust me.

One thing that I am very glad I have is the trusty Shop Vac! We got a Sears gift certificate from my uncle when we got married 14 years ago & this is what we got. I still love it.
This job is messy & you'll need something to suck & blow the mess with.


The main shaping tools I used were my drill press with a sanding drum and my roto zip (sears version) with a flex shaft and some kind of cone shaped stone bit. I used the drill press to shape all the ledges, pool, and protruding stones. The roto zip for all the detail work.


I used my belt sander to round off the main body corners and trim fit the main body to fit in the tank. (keep in mind, you can do all of this without these power tools. They just make it easier & neater IMO)


I used a sheet rock saw to cut the pieces off of the big sheet of Styrofoam. I started with an electric knife (which works awesome for soft foam like chair cushions) but it bogs down and heats up.
The chisel was used when I counter sunk the ledges and pool, to scrape it evenly.


A scroll saw was used to cut the protruding rocks and ledges. It cuts Styrofoam like butter. (once again, I had it so I used it, but not necessary)


Okay,, this one isn't really a tool but it saved me some $$ It's an expanding foam tool cleaner. I knew I wouldn't be doing all the great stuff at one time & those cheap applicator tubes are pretty much a one time use so I got this stuff. I got it at a Hall's (like an ACE Hardware). It's just Acetone in a can but I didn't feel like dealing with where to dispose of the used Acetone if I had bought the regular acetone in the big can. I wanted to keep this as easy as possible.

Here We Go!!

This is the main body & the tank it's going in. I'm putting a wet / dry of sorts in the back along with a Fluval 2 plus internal filter as the return. This will all be hidden behind the wall.
I just cut two strips for each side to bring the wall forward and glued them with greatstuff. I've seen some who have used silicone to glue the pieces together but I can't see trying to shape it evenly, through the silicone. Greatstuff is easy to shape. I also added some extra greatsuff on the inside corners incase I carved in to deep and for some added structural support. You can also see the file I started shaping with. It works and is easy but I didn't like the texture it was leaving. It kind of rips it apart, leaving the "beads". If you used a sander it's nice & smooth & doesn't look like broken Styrofoam.


Here is the top pool. This is where the return line will "dump" the water so it can begin it's journey down the river and back to the main tank. I stacked the blocks of styrofoam and glued them together.


Here's a top view of the pool. You can see the bumpy beads caused from the ripping of the file. It's not a big deal, I just didn't like it. Most of it would be covered up by the cement so if that's all you have, it will be fine.

Okay,, where did I leave off???

Jumping forward a few steps. I have rounded the corners with the belt sander, cut out & shaped the ledge work, and inlayed the pool & ledges. After I cut & shaped them, I traced them out on the main body. I used a flat sanding drum on my roto zip and dug it out. Then I used the chisel to flatten it all out, inside. It doesn't have to be perfect. The Great Stuff will fill any gaps. You just have to make sure it will all fit in.
Oh,, I inlayed the ledges to give it more support. I was afraid that if I just stuck them on, they might just snap off.


Here it is with the ledges in place. I've also sketched the rock work. I did however first cut out and shape all the protruding rocks first! I put them where I wanted them, traced them, then drew the rest of the rocks on. Don't try to fit extra rock in after you drew where you want to cut. It would be a pain. Also,, number the areas for your protruding rocks (and number the rocks them selves) It will be easier to put the puzzle back together later. You don't want to shape the areas where you'll be mounting the rocks. You do that later.
One more thing!!!!!!!! If you want the river to "run" make sure you use a level. If the ledges don't slope, it won't go where you want it to. LOL

Gotta love the flex shaft!! LOL My hand was numb for a couple days after this. What pain staking work! When it all starts taking shape though,, it's all worth it.
I just used the cone shaped bit and went to town. Make it as deep as possible (without going through the styrofoam). Try to round the rocks off as much as possible, meaning try not to leave a flat front. Also, I should have said this in the last post. When you’re sketching the rocks you'll start to see voids or areas where the rocks don't quite match up. Don't try to make the rocks fit in all those spaces. You'll wind up with pointy, out of place looking shapes. Just keep them individual random rocks and remove the extra, when you're shaping. It will wind up looking much more natural. I caught this happening when I was about a quarter of the way into sketching and had to go back & fix it. Also keep it random. I have seen a few projects that start to look like planted pine rows, instead of a natural forest.


Please people,,, don't forget the eye protection & dust mask. This is a messy job! You'll be coughing snow for weeks! Also, don’t carve into those protruding rock areas just yet. The rocks you already have shaped will not fit and you’ll have to do a lot of extra shaping to get them to match. I didn’t already glue the ledges & rocks on yet because it would be a pain to try and shape around them.

Okay, I did the rough detail work (will have to do some touch ups after the rocks & ledges are dry) and put everything in place. Here it is in the tank.


Once the Great Stuff is dry I'll go in and trim it all in and do the final touches.

Okay,,, I wanted to hide the top return line so I rigged this up while the rocks were drying in place. I cut two 45deg. angles in the tubing and used a lighter to melt it together.
Something like this. Well, exactly like this.


Then I drilled in from the back and the bottom of a rock I made to hide the tube. Oh,,,, I also wanted it to point down into the pool. If it was horizontal it would or might have shot out of the pool.


And this is where it will mount to. (I'll get pics from behind with all the plumbing once I get it in place.) (this pic should have been from a little further away. It's kind of hard to visualize from this close)

One quick step back. I did drill a hole for the bottom return on the right and the intake on the left. For the intake I just carved out an entire rock. I will be covering the hole with some gutter guard later.


Okay,, Time to make this thing look a little more realistic. I'm tiered of a white rock wall. Time for the Quikrete.

I used several coats of this stuff. The first few were pretty thin. I mixed it to a (quote from Joey) watered down grits consistency. You have to stop to remix this stuff fairly often. The first few coats I added a lot of the charcoal coloring. Oh,,,,, Big TIP. When you mix a color, mix it dry and save enough for another coat in another container. It's hard to make it match if you use scientific measurements like I did (oh,,, just a little more) LOL.
Also, don't make too much. It sets up fairly quickly. (keep mixing)


On the 3rd coat I tried it with no color since it's supposed to be gray. Well, it was a very pale light tint of green? And it didn't blend in what so ever. I wanted to keep the deeper grooves the dark and make it lighter on the outer surfaces. Well it was not going well so I did another dark batch and did a 4th coat. Then I added some of the charcoal color just not as much and made a lighter shade of the same color and it worked out..

Well that’s it for now. I'm being patient and letting this thing cure. I did however have to give the river ( or in this case little creek) a try. I put the return line up to my hose and gave it a shot. I'm sooooo glad I did. On left side in the turn-around pool where the water goes back to the right, a little water would run over the edge, going down the wall. My Son actually built it up a little so it would all go back to the right side as intended. We just mixed a little of the quikrete fairly thick and molded it on. See,, play dough does help you learn! LOL

I’ll get some more pics up as soon as I mount it in the tank and get the filter, etc. connected.